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3 years ago

_____ is very hot, even at night. a)Mars b)Venus c)Uranus d)Mercury

1 answer:

5 0

B. venus. although mercury is closest to the sun, venus is hotter, day & night. heat can escape mercury which is why it gets cold despite being so close to the sun. however venus is hottest because whenever heat gets there it never leaves due to the atmosphere venus has.

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What is the direction and speed of an object?

KatRina [158]

Answer:

Explanation:

Velocity by definition means speed and direction of an object. This means it has a value and a positive or minus sign indicating direction. Speed is the absolute value of velocity because there is no direction correlated with speed. If you add a direction, it is then called velocity

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4 years ago

Currents circulate in a piece of metal that is pulled through a magnetic field. What are these currents called?

MariettaO [177]

<h3>Answer;</h3>

Eddy currents

<h3>Explanation;</h3>

Eddy currents are currents which circulate in conductors like swirling eddies in a stream. These currents are induced by changing magnetic fields and flow in closed loops, perpendicular to the plane of the magnetic field.
They are created as a result of change in the intensity or direction of a magnetic field on a conductor, this occurs either when a conductor is moving through a magnetic field, or when the magnetic field surrounding a stationary conductor is varying

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3 years ago

An open container holds ice of mass 0.555 kg at a temperature of -16.6 ∘C . The mass of the container can be ignored. Heat is su

s2008m [1.1K]

Answer: A. 23.59 minutes.

B. 249.65 minutes

Explanation: This question involves the concept of Latent Heat and specific heat capacities of water in solid phase.

Latent heat of fusion is the total amount of heat rejected from the unit mass of water at 0 degree Celsius to convert completely into ice of 0 degree Celsius (and the heat required for vice-versa process).

Specific heat capacity of a substance is the amount of heat required by the unit mass of a substance to raise its temperature by 1 kelvin.

Here, given that:

mass of ice, m= 0.555 kg

temperature of ice, T= -16.6°C

rate of heat transfer, $q=820 J.min^{-1}$

specific heat of ice, $c_{i}= 2100 J.kg^{-1}.K^{-1}$

latent heat of fusion of ice, $L_{i}=334\times10^{3}J.kg^{-1}$

Asked:

1. Time require for the ice to start melting.

2. Time required to raise the temperature above freezing point.

Sol.: 1.

We have the formula:

$Q=mc\Delta T$

Using above equation we find the total heat required to bring the ice from -16.6°C to 0°C.

$Q= 0.555\times2100\times16.6$

$Q= 19347.3 J$

Now, we require 19347.3 joules of heat to bring the ice to 0°C and then on further addition of heat it starts melting.

∴The time required before the ice starts to melt is the time required to bring the ice to 0°C.

$t=\frac{Q}{q}$

$=\frac{19347.3}{820}$

= 23.59 minutes.

Sol.: 2.

Next we need to find the time it takes before the temperature rises above freezing from the time when heating begins.

Now comes the concept of Latent heat into the play, the temperature does not starts rising for the ice as soon as it reaches at 0°C it takes significant amount of time to raise the temperature because the heat energy is being used to convert the phase of the water molecules from solid to liquid.

From the above solution we have concluded that 23.59 minutes is required for the given ice to come to 0°C, now we need some extra amount of energy to convert this ice to liquid water of 0°C.

We have the equation: latent heat, $Q_{L}= mL_{i}$